Influence of solvent polarization and non-uniform ionic size on electrokinetic transport in a nanochannel

Abstract

In this paper, we study the electroosmotic transport in a nanofluidic channel by using a mean-field theory accounting for non-uniform size effect and solvent polarization effect. We witness that in the presence of the given zeta potential, an enhancement of ion size invariably lowers the electroosmotic velocity, thereby increasing the magnitude of electrostatic potential, irrespective of considering solvent polarization. It is also proved that solvent polarization allows both the magnitude of electrostatic potential and the electroosmotic velocities to decrease. In addition, we find that increasing zeta potential augments not only ion size effect but also solvent polarization effect. Furthermore, we demonstrate that decreasing bulk ion number density causes an increase in electroosmotic velocity at the centerline. We compare the properties of aqueous electrolytes with those of the electrolytes where solvent is ethylalcohol. Finally, we study how solvent polarization and ionic size affect streaming potential and electroviscous effect. It is emphasized that the present study can provide a good way to control the nanofluidic transport for a plethora of biological and industrial applications.

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